docs: def dagcircuit_to_tk(dag:DAGCircuit, _BOX_UNKNOWN:bool=BOX_UNKNOWN, _DROP_CONDS:bool=DROP_CONDS) -> Circuit :
      """Converts a :py:class:`qiskit.DAGCircuit` into a :math:`\\mathrm{t|ket}\\rangle` :py:class:`Circuit`.
      Note that not all Qiskit operations are currently supported by pytket. Classical registers are supported only as 
      the output of measurements. This does not attempt to preserve the structure 
      of the quantum registers, instead creating one big quantum register.
  
      :param dag: A circuit to be converted
  
      :return: The converted circuit
      """
      qs = dag.get_qubits()
      qnames = ["%s[%d]" % (r.name, i) for r, i in qs]
      g = dag.multi_graph
      circ = Circuit()
      if DEBUG :
          print("new graph w " + str(len(qs)) + " qubits")
          print(str(qs))
  
      # process vertices
      tk_vs = [ None for _ in range(dag.node_counter + 1) ]    
      for n in g.nodes :
          node = g.nodes[n]
          if DEBUG : 
              print(str(n) + " " + str(node["type"])+ " " + str(node["name"]))
          if ((node["type"]=="in" or node["type"]=="out") and not node["name"] in qnames) :
              # don't create vertices for in/outs of classical registers
              if DEBUG:
                  print("Dropping node " + str(n))
              continue
          else :
              tk_vs[n] = circ._add_vertex(_node_converter(circ, node, _BOX_UNKNOWN=_BOX_UNKNOWN, _DROP_CONDS=_DROP_CONDS))
              if DEBUG:
                  print("qiskit vertex " + str(n) + " is t|ket> vertex " +str(tk_vs[n]))
      # process edges
      for e in g.edges(data=True) :
          wire = e[2]["wire"]
          if wire in qs : # ignore classical wires
              src_port = _get_port_for_edge(g.node[e[0]], wire)
              tgt_port = _get_port_for_edge(g.node[e[1]], wire)
              if DEBUG : 
                  print(_make_edge_str(tk_vs[e[0]],src_port,tk_vs[e[1]],tgt_port))
              circ._add_edge(tk_vs[e[0]],src_port,tk_vs[e[1]],tgt_port)                
  
      return circ